It is well known that all types of artificial grass or turf made of conventional synthetic fibers such as polypropylene and nylon are readily disfigured by burning cigarettes which are all too often dropped on them by careless smokers. Cigarette burn scars are often seen on the surfaces of artificial grass or turf that cover the entrances to hotels, motels, office buildings, and patios. The problem involves the thermoplastic nature of the synthetic fibers (slit or split film inclined) used in the construction of the artificial grass pile and the continuous burning characteristics of cigarettes (additives, such as potassium nitrate, are added to cigarette tobacco to prevent self extinguishing).
U.S. Pat. No. 3,987,228 discloses a process for forming pile products by pressing a sheet of thermoplastic material (e.g., ethylene-vinyl acetate copolymer) against a heated surface and drawing fibrils from the surface of the sheet. The fibrils are then cross-linked while in a self-supporting position. It is noted that the cross-linking decreases the melt flow index which improves the abrasion resistance of the pile surface. It is further noted that the dimensional stability of the polymer at temperatures around its melting point is improved and the pile itself is stiffer and more resilient.